What are the reasons for the seasonal changes on the earth?

The change of the four seasons on the earth is due to the angle between the orbital planes of the earth's revolution and rotation, which causes the earth to rotate obliquely.

In different periods of the earth's revolution, the distance from the sun is different. Moreover, due to the existence of the included angle, the intensity of solar irradiation and the angle of solar rays are different in different time periods between the north and the south of the earth (the small angle of solar rays means small heat). In this way, different periods of time will have different climates. It changes all the year round. Similarly, there is only summer in the tropics, because the equator is always in direct sunlight. For the same reason, there are extreme days and nights at the poles of the earth.

The movement of the earth around the sun is called the revolution of the earth. Because there are other celestial bodies in the solar system that revolve around the sun with the earth, and the sun is their central celestial body. The direction of the revolution is also from west to east, and the revolutionary time is one year. So the revolution of the sun will also bring us changes in the four seasons, and the four seasons will also change. The force of the earth's revolution comes from the rotation of the sun, just like a shaft drives a wheel to rotate. The gravity of the sun (universal gravity) makes it impossible for the earth to fly away from the sun.

The rotation of the earth is an important movement form of the earth. The average rotation angular velocity is 4. 167× 10 (-3) degrees/second, and the rotation linear velocity on the equator of the earth is 465 meters/second. It takes 23 hours and 56 minutes for the earth to rotate once, increasing or decreasing by three thousandths to four thousandths of a second every 10 year. The rotation of the earth will produce the phenomenon of alternating day and night.